About the related art, nowadays, the known processes used up to now to separate the water molecule in hydrogen and oxygen atoms are, among others:
a).—The application of intense electrical currents.
b).—The heating of water until two thousand degrees centigrade.
c).—The separation of water molecule by solar electrochemical method: (photoelectrochemical), which integrates a semi-conductor material and a water electrolyzer in a monolithic design to produce hydrogen directly from water using light as the unique energy source. Simple in concept, the challenge was to find a material or base that could support the whole process, and up to now, the ideal or the most adequate material had not found because some materials are very expensive, some are polluting, others are inefficient; most of them decompose fast, others are damaged with water and some others require exceedingly strict work conditions; that is why cost-effectiveness has not been feasible up to now from an economical, environmental and political point of view, and others are not appropriate for large scale application, their usefulness being thus reduced to some specific and small processesd).—Another method to separate water is by solar energy concentration (with mirrors for example), with the object to elevate water temperature until two thousand ° C. This is the required temperature used in laboratory to divide the water molecule.e) One further method is by using photosynthetic microbes as green algas and cianobacterium, those produce hydrogen from water as part of metabolic activities using light energy as main source. This photobiological technology is promising, but as oxygen is produced as well as hydrogen, the technology must solve the limitation that is the sensibility to oxygen in the enzymatic systems. Besides, hydrogen production from photosynthetic organisms is currently too low to be economically viable.f).—Another method is water electrolysis, using electricity to separate the water molecule in its compounds (hydrogen and oxygen atoms). At present time, two kinds of electrolyzers are used for commercial production of hydrogen: the alkaline, and the membrane of protons interchange, but these approaches cannot compete now from an economic point of view with the hydrogen produced from natural gas. (Source: U.S. Department of Energy, Efficiency and Renewable Hydrogen fuel cells and Infrastructure Technology Program Hydrogen Production & Delivery).
A natural material that can also divide or separate the water molecule and that has been studied is chlorophyll but because its affinity with light is between 400 nm and about 700 nm the rest of the light energy is lost. That is why it is estimated that 80 percent of used energy is wasted. Moreover, its production is complex and expensive, requiring for example temperatures of −8° C. These are the reasons by which we decided to use the melanins as electrolyzing water element, because its affinity in the spectrum goes from 200 to 900 nm or more, and because of the physiological characteristics of the tissues in which melanin generally occurs. Parameters such as the oxygen concentration call the attention and that is why we decided to contrast the hypothesis that when melanin is illuminated, we would get the photolysis of the water molecules, generating thus oxygen and hydrogen atoms, besides other products such as OH, hydrogen peroxide, anion superoxide and high energy electrons, as well as support and catalyze the reverse reaction.
Before our work, the photohydrolitic and hydrosynthetic properties of melanin, the so called melanin response to electrorretinogram only had historical interest. In the early sixties, it was discovered that intense non physiological luminous stimulus applied to the pigmented ephythelium of the retina, generated potential changes throughout it. This response to melanin reflects a physicochemical response to light absorption by melanin, similar in some way to the early potential of electrorretinogram receptors generated by opsin molecules.
The literature points out that researchers have not found the clinical application to the melanin response yet. And we add that this is due to the fact that the process of said event had not been understood. Now we know that portions surrounding the molecule collect photon energy and through it the water molecule is divided, that is, they oxide it, separating hydrogen from oxygen, then the hydrogen, the carrier of energy by excellence is caught possibly by FAD and NAD for its further processing by eukaryote cell to energize one or other reaction among the many that occur every second and lead to life. But the wonder of the event is that also the structure of (primary, secondary, third, fourth) melanin permits the occurrence of the opposite reaction, i.e. the union of hydrogen and oxygen, or in other words, the reduction of oxygen, that produces water and electricity. The absorption of light by the melanin starts an ionic event that finally gives us electricity, because the sole division of water molecule is not enough; the reversibility of the reaction has to happen, i.e. the reunion of the hydrogen and oxygen atoms.